This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from an application for HORIZONTAL DISPLAY SIZE COMPENSATION CIRCUIT FOR A MONITOR earlier filed in the Korean Industrial Property Office on the Jul. 31, 1997 and there duly assigned Serial No. 21227/1997.
1. Field of the Invention
The present invention relates to a monitor, and more particularly to a horizontal display size compensation technique for a monitor which prevents a horizontal display size of a monitor screen from being changed when a horizontal frequency varies according to a video mode.
2. Description of the Prior Art
In an earlier horizontal display size compensation circuit for a monitor, a horizontal deflection oscillation section has an oscillation circuit for generating a predetermined deflection frequency by charging and discharging a capacitor. A horizontal deflection drive section is provided to amplify and correct a deflection frequency waveform of the horizontal deflection oscillation section, and a horizontal deflection output section is provided to control the current flowing in a horizontal deflection coil according to a deflection frequency of the horizontal deflection drive section. A microcomputer outputs a horizontal display size control signal according to an input signal of a key input section which is operated by a user and detects each video mode which will be outputted to a monitor screen. A horizontal frequency generation section generates a horizontal frequency according to the video mode of the microcomputer. A horizontal display size control section is provided to control a horizontal screen display size according to a horizontal frequency of the horizontal frequency generation section and a horizontal display size control signal of the microcomputer and a horizontal display size output section is also provided to supply a signal of the horizontal display size control section to the horizontal deflection output section.
When a user controls a horizontal display size compensation size through the key input section, the microcomputer outputs outputs a horizontal display size control signal to the horizontal display size control section for a screen display size. The horizontal display size control signal is supplied to the horizontal display size control section which is preset in the microcomputer in accordance with each key input. Therefore, the horizontal display size control section controls a horizontal screen display size by supplying a voltage of a horizontal display size control signal to a horizontal frequency inputted form the horizontal frequency generation section. A monitor outputs images of video modes having different resolutions, and different predetermined horizontal frequencies are outputted in accordance with the video mode and accordingly, a horizontal screen display size of a monitor freely varies by a change of a horizontal frequency according to a video mode.
Since a desired image can not be precisely displayed due to a variation of a display size according to a video mode, there exists a drawback in that a user manually corrects a horizontal display size of a monitor screen through a key input while seeing a variation of the horizontal display size when the user corrects a variation of the horizontal display size of the monitor screen according to a change of a video mode.
In order to solve the above drawback, it is an object of the present invention to provide a horizontal display size compensation technique for a monitor to compensate a horizontal display size by supplying a voltage according to a horizontal frequency, so that a variation of a horizontal display size of a monitor screen according to different video modes is prevented.
To obtain the above object, the present invention comprises: a horizontal frequency generation section for generating a horizontal frequency corresponding to each video mode; a microcomputer for outputting a horizontal display size control signal according to an input of a key input section, and for outputting a predetermined horizontal display size compensation signal according to the horizontal frequency corresponding to a video mode; and a horizontal display size control section for controlling a horizontal display size of a monitor screen according to the horizontal frequency of the horizontal frequency generation section, the horizontal display size control signal and the horizontal display size compensation signal of the microcomputer.
Further, the horizontal display size compensation signal of the microcomputer is set to a predetermined voltage which increases in accordance with an increase of the horizontal frequency corresponding to a video mode, and the horizontal display size compensation signal is preferably supplied with a horizontal frequency which is inputted from the horizontal frequency generation section to the horizontal display size control section.